I did select everything. I suspect this was because I had several objects while Panda expects only one.
I don’t know how to make several meshes inside a single object. However, I got things to work by Joining my two doors. I have only one mesh, but by affecting each half-mesh to its own vertex group, the export almost worked. I still had to hack into the egg to delete joints that were present twice, but it works now.
I’ll look into having two meshes into one object, because the way I’m doing it isn’t super handy.
All of that will seem so obvious after the fact…